Light emitting diode

ABSTRACT

A LED chip including a substrate, a semiconductor device layer, a current blocking layer, a current spread layer, a first electrode and a second electrode is provided. The semiconductor device layer is disposed on the substrate. The current blocking layer is disposed on a part of the semiconductor device layer and includes a current blocking segment and a current distribution adjusting segment. The current spread layer is disposed on a part of the semiconductor device layer and covers the current blocking layer. The first electrode is disposed on the current spread layer, wherein a part of the current blocking segment is overlapped with the first electrode. Contours of the current blocking segment and the first electrode are similar figures. Contour of the first electrode and is within contour of the current blocking segment. The current distribution adjusting segment is not overlapped with the first electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of patent application Ser. No.12/397,353, filed on Mar. 4, 2009, now allowed, which claims thepriority benefit of Taiwan patent application serial No. 97148836, filedon Dec. 15, 2008. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-emitting diode (LED) chip. Moreparticularly, the present invention relates to a LED chip where acurrent distribution therein can be adjusted.

2. Description of Related Art

With development of semiconductor technology, a present LED may achievea high-brightness output, and since the LED has advantages ofpower-saving, small-size, low power driving and non-mercury, etc., ithas been widely used in displays and illumination devices, etc.Generally, a light-emitting efficiency of a LED chip relates to internalquantum efficiency (i.e. light-extraction efficiency) of the LED chip.When the light emitted from a light-emitting layer has a highertransmittance with respect to the LED chip, it represents that the LEDchip has good light-emitting efficiency.

Electrodes of the LED chip are generally fabricated by metal materials,and since the metal materials are opaque, the light emitted from aregion under the electrode of the LED chip may be blocked, which maycause a waste of power. Therefore, a technique of forming a currentblocking layer between the electrode and the semiconductor device layeris developed.

FIG. 1A is top view of a conventional LED chip having a current blockinglayer. FIG. 1B is a cross-sectional view of the LED chip of FIG. 1Aalong the I-I′ line. Referring to FIG. 1A and FIG. 1B, the LED chip 100includes a substrate 110, a semiconductor device layer 120, a currentblocking layer 130, a current spread layer 140, a first electrode 150and a second electrode 152. The semiconductor device layer 120 includesa first type semiconductor layer 122, a light-emitting layer 124 and asecond type semiconductor layer 126.

As shown in FIG. 1A and FIG. 1B, the second electrode 152 is disposed onthe first type semiconductor layer 122. The first electrode 150 isdisposed on the second type semiconductor layer 126, and the currentblocking layer 130 is disposed between the first electrode 150 and thesecond type semiconductor layer 126. Moreover, the current spread layer140 is disposed between the first electrode 150 and the second typesemiconductor layer 126, and covers the current blocking layer 130entirely, wherein a shape of the current blocking layer 130 and a shapeof the first electrode 150 are similar figures, and an area of thecurrent blocking layer 130 is slightly greater than that of the firstelectrode 150. The current blocking layer 130 is used to block thecurrent passing through an area covered by the current blocking layer130. If the LED chip 100 does not have the current blocking layer 130,the light emitted from the light-emitting layer 124 under the firstelectrode 150 can be shielded by the first electrode 150, which may leadto a poor light-emitting efficiency of the whole LED chip 100. If theLED chip 100 has the current blocking layer 130, the light-emittinglayer 124 located at a region under the current blocking layer 130 doesnot emit light or only emits few light, while the light-emitting layer124 located at a region other than that under the current blocking layer130 can emit light without being shielded by the first electrode 150.Therefore, waste of the power at the region under the first electrode150 can be reduced by applying the current blocking layer 130.

SUMMARY OF THE INVENTION

The present invention is directed to a LED chip having a currentblocking layer for adjusting a current distribution in the LED chip.

The present invention provides a LED chip including a substrate, asemiconductor device layer, a current blocking layer, a current spreadlayer, a first electrode and a second electrode. The semiconductordevice layer is disposed on the substrate. The current blocking layer isdisposed on a part of the semiconductor device layer, wherein thecurrent blocking layer includes a current blocking segment and a currentdistribution adjusting segment. The current spread layer is disposed ona part of the semiconductor device layer and covers the current blockinglayer. The first electrode is disposed on the current spread layer,wherein a part of the current blocking segment is overlapped with thefirst electrode. A contour of the current blocking segment and a contourof the first electrode are similar figures, and the contour of the firstelectrode is within the contour of the current blocking segment. Thecurrent distribution adjusting segment is not overlapped with the firstelectrode. Moreover, the second electrode is disposed on thesemiconductor device layer.

In an embodiment of the present invention, the semiconductor devicelayer includes a first type semiconductor layer, a light-emitting layerand a second type semiconductor layer, wherein the light-emitting layeris located on a part of the first type semiconductor layer, and thesecond type semiconductor layer is located on the light-emitting layer.

In an embodiment of the present invention, the current block layer isdisposed on a part of the second type semiconductor layer.

In an embodiment of the present invention, the current spread layer isdisposed on the current blocking layer and a part of the second typesemiconductor layer.

In an embodiment of the present invention, the current blocking segmentand the current distribution adjusting segment are connected.

In an embodiment of the present invention, the current distributionadjusting segment is extended from an edge of the current blockingsegment towards an edge of the semiconductor device layer.

In an embodiment of the present invention, the current distributionadjusting segment has a plurality of openings or notches, and thecurrent spread layer is electrically connected to the semiconductordevice layer through the openings or the notches.

In an embodiment of the present invention, the openings or the notchesof the current distribution adjusting segment are bar-shape slits.

In an embodiment of the present invention, the current blocking segmentand the current distribution adjusting segment are separated.

In an embodiment of the present invention, the current distributionadjusting segment is distributed at two sides of the second electrode.

In an embodiment of the present invention, a material of the currentblocking layer includes a-SiC based material.

In an embodiment of the present invention, the SiC based materialincludes SiO_(x)C_(y):H, SiC, SiC_(x)N_(y) or SiO_(x)C_(y)N_(z).

In an embodiment of the present invention, a material of the currentblocking layer includes silicon oxide, silicon nitride or siliconoxy-nitride.

As described above, the LED chip of the present invention has thecurrent blocking layer, and the current blocking layer includes thecurrent blocking segment and the current distribution adjusting segment.Therefore, a current distribution in the LED chip can be adjustedaccording to a distribution or pattern of the current distributionadjusting segment.

In order to make the aforementioned and other objects, features andadvantages of the present invention comprehensible, a preferredembodiment accompanied with figures is described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1A is top view of a conventional LED chip having a current blockinglayer.

FIG. 1B is a cross-sectional view of a LED chip of FIG. 1A along a I-I′line.

FIG. 2 is a three-dimensional view of a LED chip according to anembodiment of the present invention.

FIG. 3 is a top view of a LED according to another embodiment of thepresent invention.

FIG. 4A is a top view of a LED chip according to still anotherembodiment of the present invention.

FIG. 4B is a cross-sectional view of a LED chip of FIG. 4A along aII-II′ line.

DESCRIPTION OF EMBODIMENTS

FIG. 2 is a three-dimensional view of a LED chip according to anembodiment of the present invention. Referring to FIG. 2, the LED chip200 a of the present embodiment includes a substrate 210, asemiconductor device layer 220, a current blocking layer 230 a, acurrent spread layer 240, a first electrode 250 a and a second electrode252 a. The semiconductor device layer 220 is disposed on the substrate210. The current blocking layer 230 a is disposed on a part of thesemiconductor device layer 220, wherein the current blocking layer 230 aincludes a current blocking segment 232 a and a current distributionadjusting segment 234 a. Moreover, the current spread layer 240 isdisposed on a part of the semiconductor device layer 220 and covers thecurrent blocking layer 230 a. The first electrode 250 a is disposed onthe current spread layer 240, wherein a part of the current blockingsegment 232 a is overlapped with the first electrode 250 a. A contour ofthe current blocking segment 232 a and a contour of the first electrode250 a are similar figures, and the contour of the first electrode 250 ais within the contour of the current blocking segment 232 a. The currentdistribution adjusting segment 234 a is not overlapped with the firstelectrode 250 a. Moreover, the second electrode 252 a is disposed on thesemiconductor device layer 220.

In present embodiment, the semiconductor device layer 220 includes afirst type semiconductor layer 222, a light-emitting layer 224 and asecond type semiconductor layer 226, wherein the light-emitting layer224 is located on a part of the first type semiconductor layer 222, andthe second type semiconductor layer 226 is located on the light-emittinglayer 224.

As shown in FIG. 2, the first electrode 250 a and the second electrode252 a are not located on a same plane, wherein the first electrode 250 ais located on the second type semiconductor layer 226, and the secondelectrode 252 a is located on the first type semiconductor layer 222.Namely, a position of the second electrode 252 a is substantially lowerthan that of the first electrode 250 a.

As shown in FIG. 2, the current blocking layer 230 a of the presentembodiment is disposed on a part of the second type semiconductor layer226. The current spread layer 240 is disposed on the current blockinglayer 230 a and a part of the second type semiconductor layer 226. Itshould be noted that the current blocking segment 232 a and the currentdistribution adjusting segment 234 a are physically separated.Particularly, the current distribution adjusting segment 234 a isdistributed at two sides of the second electrode 252 a. However, inother embodiments, the current blocking segment 232 a and the currentdistribution adjusting segment 234 a can be connected to each other.

A material of the current blocking layer 230 a includes a SiC-basedmaterial. In detail, in an exemplary embodiment, the SiC based materialincludes SiO_(x)C_(y):H, SiC, SiC_(x)N_(y) or SiO_(x)C_(y)N_(z). Inother embodiments, the material of the current blocking layer 230 aincludes silicon oxide, silicon nitride or silicon oxy-nitride.

In the present embodiment, the current blocking layer 230 a is disposedunder the first electrode 250 a, and the current distribution adjustingsegment 234 a of the current blocking layer 230 a is further disposed onthe second type semiconductor layer 226 and is located at two sides ofthe second electrode 252 a. In this way, the current cannot pass througha region where the current blocking layer 230 a is allocated. Therefore,current density of the central area in the LED chip 200 a where thecurrent blocking layer 230 a is not allocated is increased. In otherwords, under a same driving current, a light-emitting brightness of thecentral area in the LED chip 200 a where the current blocking layer 230a is not allocated can be increased.

In the aforementioned embodiment, by applying the current blockingsegment 232 a and the current distribution adjusting segment 234 a ofthe current blocking layer 230 a, the current of the LED chip 200 a canbe adjusted to a predetermined area. In the following embodiment, othertypes of current blocking layer are described in detail with referenceof other figures.

FIG. 3 is a top view of a LED according to another embodiment of thepresent invention. Referring to FIG. 3, a structure of the LED chip 200b of the present embodiment is similar to that of the LED 200 a exceptthat shapes and distribution positions of a first electrode 250 b, asecond electrode 252 b and a current blocking layer 230 b are different.

As shown in FIG. 3, the first electrode 250 b and the second electrode252 b all have a U-shape, and are disposed in interlace. It should benoted that the first electrode 250 b and the second electrode 252 b arenot located on the same plane, wherein the first electrode 250 b islocated on the second type semiconductor layer 226, and the secondelectrode 252 b is located on the first type semiconductor layer 222.Namely, a position of the second electrode 252 b is substantially lowerthan that of the first electrode 250 b.

In the present embodiment, the current distribution adjusting segment234 b is extended from an edge of the current blocking segment 232 btowards an edge of the semiconductor device layer 220. Therefore, thecurrent cannot pass through a region near the edge of the semiconductordevice layer 220. In other words, the current can be controlled to justflow through a region on the LED chip 200 b where the current blockinglayer 230 b is not distributed.

FIG. 4A is a top view of a LED chip according to still anotherembodiment of the present invention. FIG. 4B is a cross-sectional viewof the LED chip of FIG. 4A along a II-II′ line. Referring to FIG. 4A andFIG. 4B, a structure of the LED chip 200 c of the present embodiment issimilar to that of the LED chip 200 a in FIG. 2 wherein, including butnot limited, the first electrode 250 c and the second electrode 252 c ofthe LED chip 200 c are corresponding to the first electrode 250 a andthe second electrode 252 a of the LED chip 200 a respectively, exceptthat the current distribution adjusting segment 234 c of the currentblocking layer 230 c in the present embodiment has a plurality ofopenings 235, and the current spread layer 240 is electrically connectedto the semiconductor device layer 220 through the openings 235. Itshould be noted that the current blocking segment 232 c and the currentdistribution adjusting segment 234 c of the current blocking layer 230 cof the present embodiment are connected.

In the present embodiment, the openings 235 are bar-shape slits, and inother embodiments, the openings 235 can be extended to the edge of thesemiconductor device layer 220 such that a plurality of notches can beformed.

In summary, the LED chip of the present invention has the currentblocking layer, and the current blocking layer includes the currentblocking segment disposed under the first electrode and the currentdistribution adjusting segment, so that the current cannot pass throughthe current blocking segment and the current distribution adjustingsegment, and is transferred to the other regions of the LED chip.Moreover, the position of the current distribution adjusting segmentlayer can be adjusted according to actual requirements, so as to improvethe overall light-emitting efficiency of the LED chip.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A light-emitting diode (LED) chip, comprising: a substrate; asemiconductor device layer disposed on the substrate; a current blockinglayer disposed on the semiconductor device layer and having a pluralityof openings or notches; a current spread layer covering the currentblocking layer and electrically connected to the semiconductor devicelayer through the plurality of openings or notches; a first electrodedisposed on the current spread layer, wherein the first electrode doesnot overlap with the plurality of openings or notches; and a secondelectrode disposed on the semiconductor device layer, wherein thecurrent blocking layer, the current spread layer, the first electrodeand the second electrode are located on one side of the semiconductordevice layer opposite to the substrate, wherein the first electrodeextends along a direction toward the second electrode, and a first groupand a second group of the openings or notches are distributed at twosides of the first electrode, and wherein the plurality of openings ornotches comprise bar-shape slits not parallel with the first electrode.2. The LED chip as claimed in claim 1, wherein the first group and thesecond group of the openings or notches are distributed symmetrically atthe two sides of the first electrode.
 3. The LED chip as claimed inclaim 1, wherein the semiconductor device layer comprises: a first typesemiconductor layer; a light-emitting layer; and a second typesemiconductor layer, wherein the light-emitting layer is located on apart of the first type semiconductor layer, and the second typesemiconductor layer is located on the light-emitting layer.
 4. The LEDchip as claimed in claim 3, wherein the current block layer is disposedon a part of the second type semiconductor layer.
 5. The LED chip asclaimed in claim 3, wherein the current spread layer is disposed on thecurrent blocking layer and a part of the second type semiconductorlayer.
 6. The LED chip as claimed in claim 1, wherein the currentblocking layer extends to an edge of the semiconductor device layer. 7.The LED chip as claimed in claim 1, wherein the current blocking layerextends to two sides of the second electrode.
 8. The LED chip as claimedin claim 1, wherein a material of the current blocking layer comprises aSiC-based material.
 9. The LED chip as claimed in claim 8, wherein theSiC-based material comprises SiOxCy:H, SiC, SiCxNy or SiOxCyNz.
 10. TheLED chip as claimed in claim 1, wherein a material of the currentblocking layer comprises silicon oxide, silicon nitride or siliconoxy-nitride.
 11. A light-emitting diode (LED) chip, comprising: asubstrate; a semiconductor device layer disposed on the substrate; acurrent blocking layer disposed on one side of the semiconductor devicelayer opposite to the substrate and comprising a current blockingsegment and a current distribution adjusting segment; a current spreadlayer disposed on one side of the semiconductor device layer opposite tothe substrate and covering the current blocking layer; a first electrodedisposed on one side of the current spread layer opposite to thesubstrate and comprising a first portion and a second portion; and asecond electrode disposed on one side of the semiconductor device layeropposite to the substrate and comprising a first portion and a secondportion located at two sides of the second portion of the firstelectrode, and the second portion of the second electrode is locatedbetween the first portion and the second portion of the first electrode;wherein the first electrode has a contour within the contour of thecurrent blocking segment and does not overlap with the currentdistribution adjusting segment, and the current distribution adjustingsegment extends from the current blocking segment toward an edge of thesemiconductor device layer away from the second electrode.
 12. The LEDchip as claimed in claim 11, wherein the current distribution adjustingsegment is formed in a bar shape along the first portion of the firstelectrode.
 13. The LED chip as claimed in claim 11, wherein thesemiconductor device layer comprises: a first type semiconductor layer;a light-emitting layer; and a second type semiconductor layer, whereinthe light-emitting layer is located on a part of the first typesemiconductor layer, and the second type semiconductor layer is locatedon the light-emitting layer.
 14. The LED chip as claimed in claim 13,wherein the current block layer is disposed on a part of the second typesemiconductor layer.
 15. The LED chip as claimed in claim 13, whereinthe current spread layer is disposed on the current blocking layer and apart of the second type semiconductor layer.
 16. The LED chip as claimedin claim 11, wherein a material of the current blocking layer comprisesa SiC-based material.
 17. The LED chip as claimed in claim 16, whereinthe SiC-based material comprises SiOxCy:H, SiC, SiCxNy or SiOxCyNz. 18.The LED chip as claimed in claim 11, wherein a material of the currentblocking layer comprises silicon oxide, silicon nitride or siliconoxy-nitride.